Typical of the prior art problems to which this invention addresses itself are the following:
U.s. pat. No. 3,797,887, Barecki et al., Mar. 19, 1974; PA1 U.s. pat. No. 3,619,004, McKernan, Nov. 9, 1971; PA1 U.s. pat. No. 3,619,006, Barecki, Nov. 9, 1971; PA1 U.s. pat. No. 3,482,875, Barecki et al., Dec. 9, 1969; PA1 U.s. pat. No. 3,747,979, Barecki, July 24, 1973; PA1 U.s. pat. No. 3,632,159, Barecki, Jan. 4, 1972; PA1 U.s. pat. No. 3,870,363, Barecki, Mar. 11, 1975.
Many of the problems with the prior art relate to the almost universally-adopted construction which involves a seat frame which holds and supports some form of seat shell adapted to receive the body of the passenger. A typical seat frame is shown in FIG. 6 of the Barecki U.S. Pat. No. 3,797,887, while a typical seat shell is illustrated in FIGS. 1-4 of the same patent, including padding or cushion members.
In the past, it has been generally accepted in the industry that some form of seat frame would be necessary in connection with passenger vehicle seats, in order to provide the requisite strength and load-carrying capacity. Most areas on the North American continent provide for rigorous tests to be applied to seating construction before it can be installed and utilized in public transit vehicles. A typical test for a "two-wide" wall supported and cantilevered seat construction involves subjecting the seat to an impact from behind by a 600-pound weight travelling at a specified speed. The seat construction must absorb a specified amount of energy without buckling, while a high-energy impact must cause buckling or bending primarily or only at the joint between the back section and the seat section, instead of crumpling or buckling the back or seat portions themselves.
These high standards for bending resistance and load capacity have resulted in the current tendency to provide seating constructions utilizing seat frame supporting seat shells. From the disclosures of the above-referenced patents, it is quite clear that the industry has persuaded itself that only the provision of a seat frame can satisfy the rigorous strength requirements which the relevant authorities have established.
One of the primary disadvantages of any need to provide a seat frame in addition to a seating shell is the additional expense involved. Furthermore, since for double or triple seat complexes the seat frame almost invariably spans all of the seats, the double or triple seat construction when assembled is bulky and difficult to manoeuvre. If the seat shells and the seat frame are assembled together and to the vehicle at the same time, considerable man-hours are required for the assembly in situ. If the double or triple seat construction is assembled at a factory and then later installed in a vehicle, the assembly man-hours are still required (although in a different location), and in addition the completed item is bulky, heavy, and very awkward to move into its proper location.
Another difficulty related to the prior art has to do with handhold locations or "grab" bars and rails associated with the seating construction. It is usually considered desirable (and in some areas it is required by law) to provide some form of rail or "grip" which a seated passenger can use to steady himself as he stands up, and which a standing passenger can also hold to maintain balance. A typical provision is that shown in the U.S. Pat. No. 3,979,887, referred to above, which involves a bar or rail securely fixed to the seat frame, and raised above the seating shell far enough to permit it to be held in the hand. Aside from the rather awkward, utilitarian and unaesthetic appearance of hand rails of this type, there have been the more serious disadvantages of the risk of hands, wrists and arms being caught between the bar or rail and the top of the seat proper, not to mention entanglement with handbag straps, umbrellas, coat buttons and so forth. Additionally, during accidents or sudden stops of the vehicle a passenger sitting behind such a bar is in serious danger of damage to his face, and particularly the teeth due to impact with such a rail, which is ordinarily unpadded and uncovered. Finally, since the hand bar or rail represents an additional element in the construction of the seat, it naturally represents an additional expense.
A further disadvantage in the prior art constructions had to do with a tendency to apply the cushion or padding material in such a way that it was firmly affixed or adhered to the seating shell, in order to minimize the risk that it might be stolen, ripped or vandalized in same way. Typically, this called for the provision and affixing of the padding or cushion material directly to the seat shell prior to the installation of the seat shell on the seat frame. Due to this necessity, any flexibility with regard to particular patterns or colours for the cushion or padding material was severely restricted. For example, if a transport bus manufacturer were to receive an order for a vehicle having a specific one of, say, a dozen or more different types and colours of cushion material on the seats, probably also calling for a specific "matching" colour or pattern for the floor carpeting in the interior, all such interior decoration would have to be carried out after the order was received (since it clearly would not be practical to keep on stock a large number of completed vehicles with their interiors finished in all of the different patterns and varieties offered). In the past, this procedure has usually meant that at least the seat shell with the cushions firmly and non-removably affixed thereto had to be installed after the order was received, and this invariably represented a delay in the delivery of the vehicle. In some cases, where the entire seat combination including the seat frame, the seat shells and the cushions were assembled into complete units outside the vehicle and stored, it has been necessary to install all of the seating in the vehicle after the order is received. Furthermore, either of the just-mentioned methods required a very large storage space for storing the pre-assembled seating modules in the various different colours, patterns, etc. offered by the manufacturer.
In view of the foregoing difficulties and disadvantages in the prior art, this invention addresses itself to the provision of a seat construction for transit vehicles in which the seat frame familiar in the prior art is dispensed with due to a particular shape and configuration of the seating shell, which configuration is capable of developing sufficient strength and buckle-resistance to meet the standards generally applied to such structures. In effect, the stress-resisting properties of the prior art seat frames are taken by the skin of the seat shell itself, whereby a "stressed skin" construction is provided. This is similar to what occurs in many modern aircraft, in which at least a portion of the strength of the craft resides in its skin, thus minimizing the additional frame members required to bring the body up to design strength.
This invention also addresses itself to the provision of a seat construction for transit vehicles which integrally incorporates one or more "handhold" locations which are free of the disadvantages of the prior art grab rails discussed previously. Finally, this invention addresses itself to the provision of a seat construction for transit vehicles in which the padding or cushion members are designed in such a way as to minimize the risk of theft, damage or vandalism, and moreover are designed so that they may be affixed to the remainder of the seat construction after the seat construction has been assembled together and installed in the vehicle, such that the time elapsing between the selection of a particular pattern or colour scheme for the interior decoration of the vehicle and the delivery of a vehicle fitting the desired specifications is very substantially reduced. Moreover, the requirement for storing only the cushion or padding elements obviously decreases the amount of storage space necessary for a manufacturer of transit vehicles.